The present invention provides a two-step process for the preparation of pesticidal fluoroolefin compounds of formula I 
wherein
R is hydrogen or C1-C4-alkyl, and
R1 is C1-C4-alkyl or cyclopropyl, or
R and R1 are taken together with the carbon atom to which they are attached to form a cyclopropyl group;
Ar is phenyl which is unsubstituted or substituted with any combination of from one to three halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups, or
1- or 2-naphthyl which is unsubstituted or substituted with any combination of from one to three halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups;
Ar1 is phenoxyphenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups,
biphenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy Or C1-C4-haloalkoxy groups,
phenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups,
benzylphenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups, or
benzoylphenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups,
which comprises reacting fluorobromoolefin compounds of formula II 
wherein Ar, R and R1 are as described above, with organozinc compounds of formula III or IV 
wherein Ar1 is as described above, in the presence of a palladium catalyst and a solvent,
which compounds of formula II are obtained by reacting aldehyde compounds of formula V 
wherein Ar, R and R1 are as defined above, with
(a) fluorotribromomethane,
(b) a tri(substituted)phosphine or a hexaalkylphosphoramide or a mixture thereof, and
(c) zinc,
in the presence of a solvent.
In compounds of formula I, the configuration of the groups ArCRR1- and xe2x80x94CH2Ar1 about the double bond is preferably predominately mutually trans. xe2x80x9cPredominately transxe2x80x9d means that the trans-compound is present at a percentage of at least 80%, preferably above 95%.
The present invention also relates to the fluorobromoolefin compounds of formula II.
Pesticidal fluoroolefin compounds and processes for their preparation are described in WO 94/06741 and GB-A 2 288 803.
However, those processes are not entirely statisfactory because the fluoroolefin compounds are produced in relatively low yields from multi-step processes.
It was therefore an object of the present invention to provide an improved process for the preparation of fluoroolefin compounds.
Accordingly, a two-step overall process for the preparation of fluoroolefin compounds of formula I starting form aldehyde compounds of formula V, via intermediate compounds of formula II, has been found.
Furthermore, compounds of formula II have been found.
Advantageously, the inventive process affords compounds of formula I which are predominately in the trans-configuration.
WO 94/06741 and GB-A 2 288 803 disclose that fluoroolefin compounds are obtained in four steps starting from aldehyde compounds of formula V.
Exemplary of halogen hereinabove are fluorine, chlorine, bromine and iodine;
The term xe2x80x9calkylxe2x80x9d is defined as a saturated, straight or branched chain hydrocarbon with 1 to 4 carbon atoms, such as methyl, ethyl, propyl, 1-methyl-ethyl, butyl, 1-methyl-propyl, 2-methyl-propyl and 1,1-dimethyl-propyl.
The term xe2x80x9calkoxyxe2x80x9d is defined as a saturated, straight or branched chain hydrocarbon with 1 to 4 carbon atoms (as described above) which is bond to the backbone via an oxygen (xe2x80x94Oxe2x80x94) atom;
The term xe2x80x9chaloalkylxe2x80x9d is defined as an alkyl group, as defined above, wherein the hydrogen atoms may be partially or totally substituted with halogen atoms as defined above, wherein the halogen atoms may be the same or different, for example C1-C2-haloalkyl such as chloro-methyl, bromomethyl, dichloro-methyl, trichloro-methyl, fluoro-methyl, difluoro-methyl, trifluoro-methyl, chloro-fluoro-methyl, dichlorofluoro-methyl, chloro-difluoro-methyl, 1-chloro-ethyl, 1-bromo- ethyl, 1-fluoro-ethyl, 2-fluoro-ethyl, 2,2-difluoro-ethyl, 2,2,2-trifluoro-ethyl, 2-chloro-2-fluoro-ethyl, 2-chloro-2,2-difluoro-ethyl, 2,2-dichloro-2-fluoro-ethyl, 2,2,2-trichloro-ethyl and pentafluoro-ethyl, wherein the halogen atoms may be the same or different.
The term xe2x80x9chaloalkoxyxe2x80x9d is defined as an alkoxy group as defined above, wherein the hydrogen atoms may be partially or totally substituted with one or more halogen atoms as defined above, wherein the halogen atoms may be the same or different.
Wavy lines in structural formulae depict the carbonxe2x80x94carbon double bond in both the E- or the Z- isomeric configuration.
Groups containing two or more rings, such as phenoxyphenyl, biphenyl, benzylphenyl and benzoylphenyl, which may be substituted, may be substituted on either ring unless otherwise specified herein.
In a preferred embodiment of the present invention, a fluorobromoolefin of formula II is reacted with at least one molar equivalent, such as 1 to 2 molar equivalents, of an organozinc compound of formula III or IV, and 0,001 to 0,2, preferably 0,01 to 0,1 molar equivalent of a palladium catalyst in the presence of a solvent, preferably in a temperature range of xe2x88x9270xc2x0 C. to 70xc2x0 C.
The product compounds of formula I may be isolated by diluting the reaction mixture with water and extracting the product with a suitable extraction solvent. In the isolation procedure, conventional extraction solvents such as ether, ethyl acetate, toluene, and dichloromethane may be utilized.
Preferred palladium catalysts for use in the present invention include, but are not limited to, bis(dibenzylideneacetone)palladium(O), tetrakis(triphenylphosphine)palladium(O), bis(acetonitrile)palladium(II) chloride, bis(triphenylphosphine)palladium(II) chloride, [1,4-bis (diphenylphosphine)butane]palladium(II) dichloride, [1,1xe2x80x2-bis(diphenylphosphino)ferrocene]palladium(II) diacetate, palladium(II) acetate, palladium(II) chloride and mixtures thereof.
Preferred solvents for use in the preparation of compounds of formula I include, but are not limited to, aromatic hydrocarbons such as toluene, benzene, xylenes and mesitylene, halogenated aromatic hydrocarbons such as chlorobenzene and fluorobenzene, carboxylic acid amides, such as N,N-dimethylformamide, ethers such as tetrahydrofuran and dioxane, and halogenated hydrocarbons such as chloroform and carbon tetrachloride, and mixtures thereof.
Preferred solvents for use in the preparation of compounds of formula I include carboxylic acid amides and ethers and mixtures thereof, preferably N,N-dimethylformamide and tetrahydrofuran and mixtures thereof.
In a preferred embodiment of the present invention for the preparation of fluorobromoolefin compounds of formula II, aldehyde compounds of formula V are reacted with at least one molar equivalent, such as 2 to 6 molar equivalents, of fluorotribromomethane, and at least one molar equivalent, such as 2 to 7 molar equivalents, of a tri(substituted)phosphine, and at least one molar equivalent, such as 1 to 4 molar equivalents, of zinc, preferably zinc dust, in the presence of a solvent, preferably in a temperature range of xe2x88x9220xc2x0 C. to 70xc2x0 C.
Preferred tri(substituted)phosphines for use in this invention include, but are not limited to, triaryl-phosphines such as tri-phenylphosphine or tri-p-tolyl-phosphine, and tri(branched C3-C6-alkyl)-phosphines such as triisopropylphosphine or triter-tiarybutylphosphine, and mixtures thereof.
Preferred tri(substituted)phosphines which produce compounds of formula II with a preferred ratio of (E):(Z)-isomer include tri-isopropylphosphine and tritertiarybutylphosphine. Preferred ratios of (E):(Z)-isomer of formula II are ratios above 1,5:1, preferably above 2,5:1, more preferably above 3,5;1 (E):(Z).
Preferred hexaalkylphosphoramides for use in the present invention include hexamethylphosphoramide or hexaethylphosphoramide, and mixtures thereof.
Preferred solvents for use in the preparation of fluorobromoolefins of formula II include, but are not limited to, ethers such as diethyl ether or tetrahydrofuran and halogenated hydrocarbons such as dichloromethane, and mixtures thereof.
More preferred solvents for use in the preparation of fluorobromoolefins of formula II include diethyl ether, tetrahydrofuran and dichloromethane, and mixtures thereof.
Starting organozinc compounds of formulae III and IV may be prepared by reacting a bromide compound of formula VI
BrCH2Ar1 xe2x80x83xe2x80x83VI 
wherein Ar1 is described above, with activated zinc (e.g., Rieke zinc) in the presence of a solvent such as tetrahydrofuran.
Aldehyde compounds of formula V may be prepared using conventional procedures known in the art, see for example: Bioorg. Med. Chem. Lett. (1998), 8(3), p. 301; Chem. Pharm. Bull. (1996), 44(10), p. 1858; Tetrahedron Lett. (1996), 37(5), 2629; J. Org. Chem. Soc. (1995), 60 (18), p. 5803; and J. Am. Chem. Soc. (1993), 115, p. 3030.
Preferred fluoroolefin compounds of formula I which may be prepared by the process of the present invention are those wherein the variables have the following meanings, each alone or in combination:
Preferred are compounds of formula I wherein R is hydrogen and R1 is isopropyl or cyclopropyl;
Also preferred are compounds of formula I wherein R and R1 are methyl;
Furthermore, preferred are compounds of formula I wherein R and R1 are taken together with the carbon atom to which they are attached to form a cyclopropyl group.
Preferred are compounds of formula I wherein Ar is phenyl which is unsubstituted or substituted with any combination of from one to three halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups.
More preferred are compounds of formula I wherein Ar is phenyl which is unsubstituted or substituted with any combination of from one to three halogen, preferably chlorine of fluorine.
Most preferred are compounds of formula I wherein Ar is 4-chlorophenyl.
Moreover, compounds of formula I are preferred wherein Ar1 is
3-phenoxyphenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups,
3-biphenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups, or
phenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-halo-alkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups.
More preferred are compounds of formula I wherein Ar1 is 3-phenoxy-phenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-halo-alkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups.
Especially preferred are compounds of formula I wherein Ar1 is 3-phenoxyphenyl which is unsubstituted or substituted with any combination of from one to six halogen, preferably fluorine.
Most preferred compounds of formula I agents are those wherein
R is hydrogen and R1 is isopropyl or cyclopropyl, or R and R1 are methyl, or R and R1 are taken together with the carbon atom to which they are attached to form a cyclopropyl group; and
Ar is phenyl which is unsubstituted or substituted with any combination of from one to three halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups; and
Ar1 is 3-phenoxyphenyl which is unsubstituted or substituted with any combination of from one to five halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy or C1-C4-haloalkoxy groups.
Preferred fluorobromoolefin compounds of formula II are those wherein R, R1 and Ar are as defined above for preferred compounds of formula I.
In a preferred embodiment of this invention, compounds of formula II are in the (E)- configuration.
Preferred compounds of formulae III, IV and V for use in the inventive process are those wherein the variables Ar, R, and R1, respectively, are as defined above for preferred compounds of formula I.